Adding heading styles/text formatting options for H1, H4 or H5 in Course Presentation

In the Course Presentation there are only 2 heading levels available for the text formatting - Heading 2 and Heading 3.

I have two courses on the workdpress website with different branding. Therefore need to have additional heading styles.

I am using h5p mods plugin, and have added styles there, but that's obviously not enough.

Would should I do to add these headings to the formatting options? 

Thank you